The present invention relates to electrically actuated valves of the type employed for control of water inlet flow to appliances, as for example, domestic dish washers and washing machines. In order to prevent overheating of the electrical actuator, it has been required to energize the water inlet valve with a very minimum of electrical power.
It has, however, been desired to eliminate the electro-mechanical programmer and to provide electronic control of the appliance program functions utilizing low voltage solid state control devices. Such electronic control requires the water inlet valve to actuate when supplied with a direct current, which may be filtered, fullwave or halfwave rectified voltage in the range 3-120 volts and to consume only about 4 watts of power. The aforesaid low power requirements for an appliance inlet valve are considered quite stringent when compared to the requirements for valve employed in appliances controlled by an electromechanical programmer switching mechanism.
In order to keep the electrical power requirement for appliance inlet valves actuation reduced to a minimum, it has been the practice to employ a solenoid powered armature-pilot valve for initiating actuation of the main inlet valve. Such an arrangement requires only a small magnetomotive force from the solenoid to move the armature for opening the pilot valve. The use of a low opening force pilot operated valve has enabled the power requirements for the solenoid to be minimized; and, thus, this type of valve has been widely used in domestic washing appliance applications. Typically, in such a valve opening the pilot valve permits pilot flow to the outlet from a control pressure chamber thereby creating a pressure differential across a diaphragm connected to the main valve, whereupon the pressure differential opens the main valve.
It has thus been desired to provide an electrically energized pilot operated water inlet valve for applicances capable of operation from a direct current power source having a very low power consumption therefrom.